Expanding arbor



May 20, 1941. R. w. CARL 42, 9

EXPANDING ARBOR Filed June 6, 1940 I a l I II I J6 4 3.1V: Carl Patented May 20, 1941 r OFICE EXPANDING ARBOR Roger W. Carl, Elmhurst, 111., assignor of twentytwo and one-half per cent to Chester W. Nusperle and twenty-two and one-half per cent to Homer E. Nusperle, both of Elmhurst, Ill.

Application June 6, 1940, Serial No. 339,204

Claims.

This invention relates to an improved expanding arbor.

One object of the invention is to provide an expanding arbor which is particularly useful for finding the true center of anything cylindrical, as for example, a valve guide of an internal combustion engine, so that the valve seat may be shaped or trued to be concentric with the true center.

Another object of the invention is to provide an expanding arbor which will, in use, effectively remove scale and carbon from the valve guide.

A still further object of the invention is to provide an arbor of this character which may be used between the centers of a turning lathe or grinding machine for truing work on the machine.

And still another object of the invention is to provide an expanding arbor having a body which is tapered toward one end and a coiled gripping member associated with the body, which gripping member will be capable of gripping uniformly the wall of a valve guide or the like for assuring that proper centering of the axis of the arbor will take place.

Other objects of the invention not mentioned hereinbefore will become apparent during the course of the following description.

In the drawing forming a part of my application:

Figure 1 is a vertical sectional view, partly in elevation, of my improved expanding arbor.

Figure 2 is a side elevation of the gripping member employed with my expanding arbor.

Referring now more particularly to the accompanying drawing, wherein like numerals of reference will be seen to designate like parts throughout the views, the numeral I indicates. in general, the body of my improved arbor. The body I is, of course, formed of heavy metal and is preferably circular in shape. At its upper end, the body is provided with an opening 2 for receiving a turning lever of any suitable design.

Substantially medially of the length of the body I, said body is reduced to define a shoulder 3 and an elongated tapered portion or shank 4. Formed on the shank 4 is a spiral thread 5. By referring to Figure 1, it will be seen that the thread 5 is substantially rectangular in contour and that said thread is of gradually increasing thickness. In other words, at its extreme upper end the thread 5 merges into the upper end of the shank 4. At its extreme lower end the thread is of considerable thickness. Medially of the length of the shank 4 the thread is substantially one-half the thickness of its thickness at its lower end. The thickness of the thread is, of course, controlled by the amount of taper of the shank 4. As will be mentioned hereinafter, the amount of taper of the shank will be dependent upon the amount of expansion to be accorded the gripping member to be described hereinafter.

Normally carried on the shank 4 is a gripping member 6. The gripping member is in the form of a spirally shaped spring element 1 having coils interengaging with the laps or coils of the thread 5. As will be seen particularly in Figure 2, the coils of the gripping member 6 are graduated in thickness. That is to say, the uppermost coils of the gripping member are relatively thin, to fit in the relatively shallow grooves defined between the uppermost coils on the shank 4, said grooves being indicated, for the sake of convenience, at 8. Near the lower end of the gripping member the coils are provided with relatively thick walls for engagement in the relatively deep troughs 9 defined by the lowermost coils of the thread 5 on the shank 4. Obviously, the thickness of the intermediate coils of the gripping member is governed by the depth of the intermediate grooves defined by said intermediate coils along the shank I.

In use, when it is desired to clean a valve guide, it is only necessary to project the shank 4, with the gripping member 6 thereon, into the guide to be cleaned, said guide being shown at IS. The gripping member is in its lowermost position on the tapered shank l so that said shank, with the gripping member thereon, will be permitted to slide freely within the guide. When the gripping member is at a sufficient depth within the guide, the lever may be inserted through the opening 2 at the upper end of the body and said body may be turned for rotating the shank 4 within the guide. Inasmuch as the g pp member 6 is no secured to the shank 4 at any point, it will be readily seen that said member will stand still in the guide while the body moves down into it lengthwise until the gripping member contacts the face of the guide over its entire length. The result of this arrangement is that a rigid alinement for the arbor with respect to the guide will be assured. Therefore, there will be no possibility of inaccuracy when grinding a valve face, using my improved arbor for a center for any means that may be selected.

It should be understood that when my improved arbor is in position, it is only necessary to rotate the shank 4 for causing the gripping member to expand into engagement with the face of the guide. It is to be particularly noted that the coils of the gripping member fit snugly in the grooves defined by the coils of the thread 5 so that there is no danger of entry of carbon into the troughs or grooves. Sticking will thus be effectually prevented.

It is desired to mention that, when the device is being moved into or out of a valve guide, the coils of the gripping member will serve as scrapers for cleaning carbon from the guide.

As shown at I! and IS in Figure 2, the extreme upper and lower ends of the gripping member 6 are projected slightly outwardly so that the gripping member will be held against rotation in the guide when said guide is being moved to operative position and the shank 4 is being turned. However, in view of the resiliency of the coils of the gripping member, the projections I! and I8 may be dispensed with, if desired.

While the invention has been described as being particularly useful for truing. valve seats and celaning valve guides, it is obvious that it may be employed between the centers of a turning lathe or grinding machine for truing up work on the machine and, when used for this purpose, it will operate in a manner identical with that heretofore described. It is also obvious that, while the coils of the gripping member are shown of a given shape, the shape may be varied to suit conditions. The shape or thickness of the gripping member may be varied without changing the shank 4, although it will be readily understood that, if the Width of the coils is enlarged or lessened, the Width of the grooves between the coils of the thread 5 must be changed accordingly.

It is thought that the construction and operation of my improved expanding arbor will now be thoroughly understood.

Having thus described the invention, what is claimed is:

v 1. An expanding arbor including a body having a tapered shank formed with a thread, and a gripping member carried on the shank and comprising a coil interengaging with the thread,

said shank being circumferentially movable for expanding the coil of the gripping member to engage a circular wall whereby the body will be alined concentrically with the wall.

2. In an expanding arbor, a body having a reduced portion defining a shank, said shank being tapered toward one end and having a spiral thread thereon, said spiral thread defining spaced grooves of gradually increasing depth toward the end of said shank, and a gripping member, said gripping member comprising a spiral element having coils engaged in the grooves, the thickness of the coils being graduated along the element so that the thickest of the coils will 'be disposed in the deepest of the grooves, said body being rotatable for expanding the coils to engage a circular wall for causing alinement of the body with respect to the wall.

3. In an expanding arbor, a tapered shank formed with a spiral thread defining troughs, and a gripping member carried by the shank and comprising a spiral element having coils engaged in the troughs, the thickness of the coils being gradually increased toward one end of the element, said shank being rotatable for expanding the coils to engage a circular surface whereby the shank will be held in alinement with said surface.

4. In a device of the character described, a body having a tapered shank formed with a thread, and a gripping member carried onthe shank and comprising a spiral element having coils engageable with the thread, rotation of the shank causing expansion of the coils of the spiral element for engaging a circular surface whereby the shank will be maintained in alinement with the circular surface.

5. An expanding arbor including a tapered portion formed with a thread, and agripping member. carried on the tapered portion and comprising a coil interengaging with the thread, said tapered portion being rotatable for expanding the gripping member.

ROGER W. CARL. 

